It is industry practice for certain information pertaining to tire, such as tire size, brand identification, inflation requirements, etc. to be integrally molded into the tire during its manufacture. With the passage of the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act, it is now a requirement that certain additional information be permanently incorporated into a tire; information that is not readily incorporated into a tire from the mold. For example, a new requirement is that the week/year of manufacture be integrally affixed to the tire in order to render certain its date of manufacture throughout the useful life of the tire. It is, however, impractical to comply with the new date code requirement by modifying the mold each week to mark the tires with the week/year of manufacture. To change a mold weekly to comply with the date code requirement of Tread Act would be unduly burdensome and would add significantly to the cost of tire manufacture.
An alternative to incorporating such information into a tire is to engrave the information into the tire by laser in a post-cure operation. In addition to information necessary for compliance with the Tread Act, it could be beneficial to integrate other information such as plant and press identification for future reference.
In order for laser engraving to be employed in permanently incorporating reference information into a tire, the means for quickly, effectively, and efficiently locating three dimensional coordinates of the tire region to be engraved is necessary. Prior techniques have centered on the use of line scan cameras that require both the tire to be chucked on a spindle and a camera mounted at a comparatively close distance. The line scan camera uses traditional edge-detection techniques to locate by edge-detection the entire image or region to be engraved. Such a technique requires an additional programmatic method to find the specific region of interest, undesirably adding a time consuming step in the tire manufacturing process.
A need accordingly exists for quickly, effectively, and efficiently locating three dimensional coordinates of the tire region to be engraved. The desired solution to the industry's need must avoid the use of edge-detection throughout an entire image and have a cycle time as short as practical. The methodology should expeditiously identify a specific region of interest through use of mathematical tools and avoid unnecessary edge detection steps.